Transient (exogenous) covert attention affects basic dimensions of vision such as contrast sensitivity, spatial resolution, and temporal resolution. Two recent studies relate such evidence to corresponding phenomenological changes, showing that the observed increase in contrast sensitivity and spatial resolution is associated with an increase in the apparent contrast and spatial frequency of the attended stimulus (Carrasco, Ling, & Read, 2004; Gobell & Carrasco, 2005). Here we explored the possibility of a phenomenological correlate of attention for temporal aspects of our visual experience. Specifically, we asked whether and how transient attention affects the perceived flicker rate of temporally modulated visual stimuli.

Methods:

We employed a psychophysical method recently developed to directly assess changes in appearance with transient attention, manipulated attention via uninformative spatial cues, and used suprathreshold Gabor stimuli that were counterphase modulated at various temporal frequencies (3.75 – 12 Hz). In each trial, two Gabors, appearing briefly (317 ms) to the left and right of fixation (1.5° eccentricity), were modulated at either the same or different rates. To assess appearance, observers were asked to perform an orientation discrimination task contingent on perceived flicker rate. “What was the orientation of the Gabor that flickered faster?”

Results:

The transient precue increased the perceived flicker rate of the temporally modulated stimuli at the cued location. A control experiment, in which observers reported the orientation of the Gabor that flickered slower, ruled out the possibility that such a result was determined by a cue bias. We conclude that transient attention increases perceived flicker rate.